Field of the Disclosure
The present application relates to apparatus and method for driving a touch screen.
Description of the Related Art
User interfaces allow user to easily and conveniently control all sorts of electric/electronic appliances. As user interfaces, key pads, keyboards, mice, on-screen displays (OSDs), remote controllers and so on are being used. The remote controller has an infrared light communication function or a radio frequency communication function. Such user interface technologies are continuously developed in order to accommodate the sensitivity of users and the convenience of manipulation. Recently, the user interfaces have evolved into touch user interfaces, voice recognition user interfaces, three-dimensional user interfaces, etc.
The touch user interfaces are being used in portable information appliances, and furthermore widely applied to home appliances. The touch user interface includes a touch screen. As an example of the touch screen, a mutual capacitive touch screen capable of sensing not only a touch but also proximity is used. Such a mutual capacitive touch screen can also detect positions of multi-touches (or multi-proximities).
The mutual capacitive touch screen includes Tx (transmitting) lines, Rx (receiving) lines and sensor nodes formed at intersections of the Tx and Rx lines. Each of the sensor nodes has a mutual capacitance. A touch screen driving apparatus senses a variation of a voltage, which is charged into the sensor node between before and after a touch or proximity, and determines whether or not a conductive object is touched or approximated and the position thereof.
Such a touch screen can be attached to or built into a display panel of a display device. The touch screen is mainly used in a small-sized display panel such as a portable information appliance. As such, a single Tx driver applying scan signals the Tx lines and a single Rx driver receiving touch sensing signals from the Rx lines are disposed on the touch screen.
Recently, the touch screen is also being used in a large-sized display panel. The touch screen used in the large-sized display panel includes far more Tx and Rx lines compared to that used in the portable information appliance. Due to this, it is difficult to drive the touch screen of the large-sized display panel using only the single Tx driver and the single Rx driver.
If a touch screen used in the portable information appliance is applied to the large-sized display panel, a distance between the Tx lines and another distance between the Rx lines must become larger. As such, accurate touch sensing signals cannot be obtained. In other words, a large-sized touch screen suitable for the large-sized display device must be used. In order to maintain or enhance touch sensitivity, the Tx lines and the Rx lines formed on the touch screen must increase. In this case, if only a single Rx driver is used, it must be generated various problems including a signal delay and so on.
Moreover, when a plurality of Rx drivers is used, abnormal touch sensing data is generated in the Rx lines opposite to edges of and boundaries between the Rx drivers.